Shears



Marc-n27, 1945. WIL 2,372,242

SHEARS Filed Oct. 9, 1945 INVENTOR 2) ATTO R N EY Gerald M55021;

Patented Mar. 27, 1945 UNITED STATES PATENT OFFICE SHEARS Gerald Wilson,Pelham Manor, N. Y.

Application October 9, 1943,'Serial No. 505,598

Claims.

This invention is an improvement in shears, and by that term I includeall apparatus or constructions for domestic, manicure, industrial, orother purposes, andin which two pivotally connected members have edges,one of which is progressively moved past the other to sever any articleor material or portion thereof projecting, between said edges. Thesepivotally connected members hereinafter referred to as blade members,may each move in respect to the other, as for instance in ordinaryshears, scissors, hedge trimmers, or other analogous devices, or onewhich may be stationary and the other movable about the pivotalconnection.

Both of the cutting edges may be substantially straight or curved moreor less away from each other, or curved in the same direction and to thesame or different extents, or one may be straight and the other convexlycurved. Either or both of the blade members may be, and preferably are,slightly curved toward the other, so that they are pressed together withthe proper pressure at the cutting point at all positions of the cuttingpoint along the length of the cutting edges.

The invention relates more particularly to the means employed forholding the cutting edges in yielding engagement with each otherthroughout the length of the cut.

I am aware that it has been proposed to use a spring at the pivotalconnection and that it has also been proposed to use a spring fulcrumedat said pivotal connection and bearing on a ball mounted in one bladeand movable along the other in a path at a short distance'behind saidconnection.

Where one or more balls have been used, they have been held in socketsso that they could not exerting pressures or forces tending to cant theblade members toward each other from the pivotal connection, and whichpressures and forces are in perfect equilibrium or balance irrespectiveof changing angles between said members during the cutting operation.

' each other.

In carrying out the invention, means are provided which tend to pressthe blade members apart at two spaced points in the rear of thepivot,and thus press the blades together at a As an important feature, thepressure or force exerted at the first mentioned two points is throughballs, roller members, or other elements which may travel transverselyof the blade member carrying them, as well as transversely of the otherblade member, as the blades move in respect to each other during openingand closing of the shears. Thus, the three points are at all times sopositioned that a line from the cutting point through the pivot fallsbetween the other two points. Preferably, this line bisects the anglebetween the two lines drawn from the cutting point through the other twopoints where pressure is applied.

The balls, roller members, or other elements are spaced apart andmaintained at substantially equal distances from the pivot. Thus, theymay roll along on both blade members, and travel through angulardistances equal to one-half the angular distance of the blades duringany given relative movement of the blades. They remain spaced to thesame distance in all normal relative positions of the blade members andthus the base of the triangle defined by the three pressure points iskept of substantially constant length.

As a further feature, a spring or other resilient means is employed, andwhich is of such a character and so positioned that equal pressure isexerted at both of said two points and at all times during thetransverse movement of said points in respect to either blade. Thus, thepressure of one blade against the other at the cutting point is properlymaintained and the blades cut as effectively at one end of the cuttingmovement as at the other.

As a further feature, the balls or other roller members travel inseparate grooves or slots, which extend in a generally arcuate directionand substantially concentric with the pivot. They may be in separatearcs of the same circle but may depart slightly from true arcs and maybe along short tangents to said arcs. As the balls in said grooves orslots travel at the same rate, they are maintained at all times atsubstantially symmetrical position in respect to a line from the cuttingpoint through the pivot.

From the standpoint of manufacture. it is in,

some respects preferable that both grooves or slots defining the path ofmovement of the balls be in'the same blade member, although from thestandpoint of operation, it is entirehr satisfactory to have one grooveor slot in one blade member and the other in the other blade member.

In the accompanying drawing:

Fig. 1 is a view in elevation showing shears embodying my invention,certain details being shown in dotted lines, a

Fig. 2 is a side elevation, a portion being shown in section,

Fig. 3 is a plan view of a portion or one of the blade members,

Fig. 4 is a view similar to a portion of Fig. 1, but showing a portionof the upper blade member broken away and the shears in closed position,

Fig. 5 is a view similar to Fig. 4, but showing the shears open to about30",

Fig. 6 is a view similar to Figs. 4 and 5, but showing the shears opento about 90,

Fig. 7 is a view similar to Fig. 3, but showing the slots of lightlymodified form.

Fig. 8 is a section through the shears in the direction ofthe length ofthe slot and on a very much enlarged scale,

Fig. 9 is a transverse section through the parts shown in Fig. 8, and

Figs. 10, 11 and 12 are diagrammatic views showing the relativepositions of the cutting point and the two rear pressure points with theblade members in the positions shown in Figs. 4, 5 and 6, respectively.

In the construction illustrated, I have shown shears which may be of anystandard shape, form, or design, except as hereinafter described, andwhich comprises a pair of blade members it and it connected by a pivotmember l2 and having'handles l3 and ll. The pivot member is shown as asimple screw with a head countersunk in the blade member ID and a shankthreaded into the blade member II. The shear members have cutting edgesl5 and 5, respectively, which may move past each other to form a cuttingpoint A, which moves progressively along the length of the cutting edgesas the shears are opened and closed.

One of the blade members here illustrated as the blade member H isprovided with a pair of grooves I7 and It in the flat face thereof,which is directly opposed to a flat face of the other blade member andin the rear of the pivot; that is, in the portion of the blade membersopposite from the cutting edges and in respect to the pivot.

The two grooves are shown in Fig. 3 as being along separate arcsconcentric with the point B, which is the axis of the pivot member l2.It is not essential that these grooves be exactly concentric or curvedbecause they may be straight, as shown at Na and I8a of Fig. 7, in whichcase the grooves are chords of the arcs. Ordinarily, the grooves extendalong about 50 or 60 of the circle around the center point B and thelength will ordinarily be determined by conditions hereinafter referredto. If the shears are to open about 90, then one end of the groove IIshould be directly in the rear of the pivot point B and one end of thegroove It should be at approximately 90 from said end of the groove H,but this angular displacement will vary according to the angle to whichthe shears may normally be wise and both he on the same side of adiameter passing through the point B.

In each groove there is mounted a roller member here shown as a ball 20.The ball projects somewhat beyond the face of the shear member II inwhich the groove is formed and contacts with the opposed face of theshear member ID. Suitable means are employed for yieldingly pressing theball into engagement with the surface of the shear member ID, and thustending to separate the shear members at the rear of the pivot andthereby press the shear members toward each other along the portionshaving the cutting edges. As shown, a, spring 2| extends lengthwise ofeach groove along the bottom thereof and has a trough or channel 22forming a track or runway for the ball. The sides of the groove may bearallel, but preferably they are made slightly diverging. as shown inFig. 9, to facilitate the cutting of the groove and the removal of thespring member, should any replacement be necessary.

When the shears are in closed position, each ball will normally. be atone end of its groove; these ends being the ends farthest around thecircumference in the same angular direction and as illustrated in Fig.4.

By reason of the spring or other yielding means, the two balls exert apressure against the blade member ID and the pressure will thus beexerted at two spaced points C and D, which are disposed on' radii fromthe pointjB, making equal angles with the main center line of the blade.As the shears are opened, the balls will travel along their respectivegrooves at the same rate and through angular distance equal to one halfthe angle between the center lines of the blades. Thus, when the bladeshave been separated to 30, the balls will have moved through 15 alongtheir grooves, and when the shears are opened to 90, the balls will movethrough 45". As the balls move at equal rates and at rates proportionalto the relative movement of the blades, the spacing between the ballswill remain constant. As one blade exerts pressure on the other at thecutting point A, and as the balls exert pressure at the points 0 and D,these three points form a triangle, which, in the embodiment shown, isasymmetrical isosceles triangle. The pivot point B is within the trianglereferred to and is preferably on the center line of the triangle.

Fig. 10 is a diagram showing the position of the pressure points A, Band C in respect to the pivot point B, and it will be noted that theline AB is a bisector of the angle CAD. As the cutting point A will movetoward the pivot point B during the opening of the shears, the samegeometric relationship will exist. Fig. 11 shows the angle between thecutting edges substant'ally 30", and Fig. 12 shows what may be theextreme position with the angle between the cutting edges substantially90. Thus, the three points at which pressure of one blade is exerted 'onthe other are symmetrically arranged and the two pressure points C and'Dare on opposite sides of and at equal distances from the line from thepressure point A to the fulcrum point B.

If the maximum opening between the cutting edges is 90, then each grooveshould extend along 45 plus an amount equal to the diameter of the ball.Obviously, if the shears are to open to a greater or lesser extent, thegrooves should be correspondingly longer or shorter. The shears 7.opened. The two grooves are spaced apart endmay be provided with anysuitable stop limiting cutting positions.

asvasca between said blade members at th opposite side distance from thepivot point B, as is the other ball, regardless of the positions of theballs in their travel along the grooves, and this applies when thegrooves are along chords of arcs as shown in Fig. '7, as well awhen-along arcs, as

shown in Fig. 3. These grooves are shown as extending only part waythrough the wall of the blade member, but obviously they might extendall the way through and constitute slots, provided that there be asuitable guideway or support for theroller member which movestherealong.

As shown, the two grooves l1 and I8 areiormed in the same blade memberand therefore arenonsymmetrically disposed in respect to the center lineof the blade. One groove may be formed in one blade member and the otherin the other blade member, in which case the grooves would besymmetrically disposed in respect to the gene'ral length of the bladeswhen in closed position. Where the cutting edges l5 and I6 are straightor are curved to the same extent and angle CAD, but if one blade bestraight and the other curved, or if the two cutting edges curve in thesame direction, the line AB will not necessarily bisect the angle CAD inall operating conditions, but it is important that the points C and D atall times be upon opposite sides of the line AB.

By means of my invention there is provided more perfect operation of theshears; the cutting blades are always maintained in contact, the properpressure is exerted on the cutting blades at the cutting point,regardless of the position of the latter, the pressure is applied atthree points spaced apart around the pivotal center, the pressure in therear of the pivot point is applied at spaced points on opposite sides ofthe line from the pivotal center to the cutting point, and the distancebetween the rear pressure points i main tained substantially constantirrespective of varying angles between the blades.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. Shears having two blade members, each presenting a cutting edge, aconnecting pivot member whereby said members have relative swingingmovement to progressively move the cuttin point along said members todifferent distances from said pivot member, a pair of spaced elementsbetween said blade members at the opposite side 01' said pivot memberfrom the cutting point and slightly spacing said blade members apart,and means whereby said elements are maintained at substantially equaldistances apart and upon opposite sides of and at equal distances froma, line intersecting said pivot member and said cutting point when saidblade members are in all normal 2. Shears having two blade members, eachpreof saidpivot member from the cutting point and slightly spacing saidblade members apart, each of said elements being movable in respect toboth of said blade members and at angular velocities in respect to saidpivot substantially equal to onehalf the angular velocities of saidblade members during relative movement of said blade members.

3. Shears having two blade members, each pre-' senting a cutting edge, aconnecting pivot member whereby said members have relative swingingmovement to progressively move the cutting point along said members todiflerent distances from said pivot member, and a pair of spacedelements between said blade members at the opposite side of said pivotmember from the cutting point and slightly spacing said blade membersapart, each of said elements being movable in respect to both or saidblade members in arcs substantially concentric with said pivot and atangular velocities substantially equal to one half the angularvelocities of said blade members during relative movement oi said blademembers.

away from each other, the line AB will bisect the l 4. Shears having twoblade members, each presenting a cutting edge, a connecting pivot mem-'ber whereby said members have relative swin ing movement toprogressively move the cutting point along said members to difierentdistances from said pivot member, and a pair of rollers slightly spacingsaid blade members apart and upon opposite sides of an extension of aline senting a cutting edge, a connecting pivot memsenting a cuttingedge, a connecting pivot mem- V ber whereby said members have relativeswinging movement to progressively move the cutting point, along saidmembers to diiferent distances from said pivot member, a pair of rollersslightlyspacing said blade members apart and upon opposite sides of anextension of a line through said cutting point and said pivot, each ofsaid rollers being movable along both of said blade members duringrelative movement of the latter, and means for applying yieldingpressure to said rollers tending to tilt the blade members likewise andto Dress them together at the cutting point.

6. Shears having two blade members, each presenting a cutting edge, aconnecting pivot member whereby said members have relative swingingmovement to progressively move the cutting point grooves spaced apartendwise, spaced from said pivot member at the side of the latterfarthest from the cutting point and extending in a general direction oftangents to a circle having said pivot member as a center, and rollermembers, one disposed in each of said grooves and movable along thegrooves as said shears are opened and closed.

7. Shears having two blade members, each presenting a cutting edge, aconnecting pivot member whereby said members have relative swingingmovement to progressively move the cutting point along said members todifferent distances from said pivot member, one of said shear membershaving a pair of grooves spaced apart endwise, spaced from said pivotmember at the side of the latter away from the cutting point andextending in a general direction or tangents to a circle having saidpivot member as a center, said grooves being non-symmetrically disposedin respect to the general center line of said blade, and a pair ofroller members, one disposed in each of said grooves and movable alongthe grooves as said shears are opened and closed.

8. Shears having two blade members, each presenting a cutting edge, aconnecting pivot member whereby said members have relative swingingmovement to progressively move the cutting point along said members todiiferent distances from said pivot member, said shears having a pair ofgrooves spaced apart endwise, spaced from said pivot member at thesideof the latter farthest from the cutting point and extending in ageneral direction of tangents to a circle having said pivot member as acenter, roller members, one disposed in each of said grooves and movablealong the grooves as said shears are opened and closed, and meansexerting a yielding pressure on said roller members and tending to presssaid blade members together at the pivot point.

9. Shears having two blade members, each presenting a cutting edge, aconnecting pivot member whereby said members have relative swingingmovement to progressively move the cutting point along said members todifferent distances from said pivot member, one of said shear membershaving a pair of grooves spaced apart endwise, spaced from said pivotmember at the side of the latter away from the cutting point andextending in a general direction of tangents to a circle having saidpivot member as a center. said grooves being non-symmetrically disposedin respect to the general center line of said blade, a pair of rollermembers, one disposed in each of said grooves and movable along thegrooves as said shears are opened and closed, and means exerting ayielding pressure on said roller members and tending to press said blademembers together at the pivot point.

10. Shears having two blade members, each presenting a cutting edge, aconnecting pivot member whereby said members have relative swingingmovement to progressively move the cutting point along said members todifferent distances from said pivot member, said shears having a pair ofgrooves spaced apart endwise, spaced 7

